Here we go again...
B&N collects your data just like Amazon does. It tracks what you are browsing and what you have purchased. This is standard practice.
B&N can pull books off of your Nook just like Amazon can pull books off your Kindle. Amazon did this once and took a huge PR hit. Bezos wrote an apology letter, gave everyone who had the book removed a gift certificate for any book they wanted, and offered the return of the book or a second gift certificate.